The iHealth-T2D study: rationale and design of a cluster randomised trial for prevention of Type 2 Diabetes amongst South Asians with central obesity and prediabetes

Abstract Background People from South Asia are at increased risk of type 2 diabetes (T2D). There is an urgent need to develop approaches for prevention of T2D in South Asians, that are cost-effective, generalisable and scalable across settings. Hypothesis Compared to usual care, risk of T2D can be reduced amongst South Asians with central obesity or raised HbA1c, through a 12 month lifestyle modification programme delivered by community health workers. Design Cluster randomised clinical trial (1:1 allocation to Intervention or Usual care), carried out in India, Pakistan, Sri Lanka, and UK, with 30 sites per country (120 sites total). Target recruitment 3,600 (30 participants per site) with annual follow-up for three years. Entry criteria South Asian, men or women, age 40-70 years with i. Central obesity (waist circumference ≥100cm in India and Pakistan; ≥90cm in Sri Lanka) and / or ii. Prediabetes (HbA1c 6.0-6.4% inclusive). Exclusion criteria: known type 1 or 2 diabetes, normal or underweight (body mass index<22kg/m2); pregnant or planning pregnancy; unstable residence or planning to leave the area; serious illness. Endpoints The primary end point is new onset T2D at 3 years, defined as: i. HbA1c≥6.5% or ii. Physician diagnosis and on treatment for T2D. Secondary endpoints at 1 and 3 years are: i. Physical measures: waist circumference, weight and blood pressure; ii. Lifestyle measures: smoking status, alcohol intake, physical activity, dietary intake; iii. Biochemical measures: Fasting glucose, insulin and lipids (total and HDL cholesterol, triglycerides); and iv. Treatment compliance. Intervention Lifestyle intervention (60 sites) or Usual care (60 sites). Lifestyle intervention was delivered by a trained community health worker over 12 months (5 one-one session, 4 group sessions, 13 telephone sessions) with the goal of the participants achieving e a 7% reduction in body mass index and a 10 cm reduction in waist circumference through i. improved diet and ii. increased physical activity. Usual care comprised a single 30 minute session of lifestyle modification advice from the community health worker. Results We screened 33,212 people for inclusion into the study. We identified 10,930 people who met study entry criteria, amongst whom, 3,682 agreed to take part in the intervention. Study participants are 49.2% female and aged 52.8 (SD 8.2) years. Clinical characteristics are well balanced between Intervention and Usual care sites. More than 90% of follow-up visits are scheduled to be complete December 2020. Based on follow-up to end 2019, the observed incidence of T2D in the study population is in line with expectations (6.1% per annum). Conclusion The iHealth-T2D study will advance understanding of strategies for prevention of diabetes amongst South Asians, use approaches for screening and intervention that are adapted for low-resource settings. Our study will thus inform the implementation of strategies for improving the health and well-being of this major global ethnic group. IRB approval 16/WM/0171 Trial registration EudraCT 2016-001350-18. Registered 14 April 2016 https://www.hra.nhs.uk/planning-and-improving-research/application-summaries/research-summaries/ihealth-t2d/ ; ClinicalTrials.gov NCT02949739 . Registered 31 October 2016, https://clinicaltrials.gov/ct2/show/NCT02949739 , First posted 31/10/2016. Funder European Commission (award 643774) and National Institute for Health Research (award 16/136/68)